# termios(3)

## NAME

         termios, tcgetattr,  tcsetattr,  cfgetispeed,  cfgetospeed,  cfsetispeed,
         cfsetospeed,  tcsendbreak,  tcdrain,  tcflush,  tcflow  - change terminal
         attributes

## SYNOPSIS

         #include <termios.h>

         int tcgetattr(int fd, struct termios *tp)
         int tcsetattr(int fd, int action, const struct termios *tp)

         speed_t cfgetispeed(const struct termios *tp)
         speed_t cfgetospeed(const struct termios *tp)
         int cfsetispeed(struct termios *tp, speed_t speed)
         int cfsetospeed(struct termios *tp, speed_t speed)

         int tcsendbreak(int fd, int duration)
         int tcdrain(int fd)
         int tcflush(int fd, int queue_selector)
         int tcflow(int fd, int action)

## DESCRIPTION

         These are the user functions that modify the tty attributes mentioned  in
         tty(4).   In the following, fd refers to an open terminal device file, tp
         is the address of a struct termios, and speed and values of type  speed_t
         are  equal to one of the B0, B50, etc. baud rate symbols.  All functions,
         symbols, and types are declared in <termios.h>.

         The effects of the tty functions are:

         tcgetattr(fd, tp)
              Get the current settings of the tty attributes.

         tcsetattr(fd, TCSANOW, tp)
              Set the terminal attributes.  The change occurs immediately.

         tcsetattr(fd, TCSADRAIN, tp)
              Set the terminal attributes.  The change occurs once all the  output
              waiting  in  the output queues has been transmitted.  This should be
              used when options affecting output are changed.

         tcsetattr(fd, TCSAFLUSH, tp)
              Set the terminal attributes.  But first wait until  all  the  output
              waiting  in  the  output  queues  has  been  transmitted.  All input
              waiting in the input queues is then  discarded  and  the  change  is
              made.   This  should  be  used when switching from canonical to non-
              canonical mode or vice-versa.  (Oddly enough, this  is  seldom  what
              you  want, because it discards typeahead.  An editing shell does the
              Right Thing if it uses TCSANOW instead.   POSIX  may  not  guarantee
              good  results, but in practice most systems make the canonical input
              available in raw mode.)

         cfgetispeed(tp)
              Return the input baud rate encoded in the termios structure.

         cfgetospeed(tp)
              Return the output baud rate encoded in the termios structure.

         cfsetispeed(tp, speed)
              Encode the new input baud rate into the termios structure.

         cfsetospeed(tp, speed)
              Encode the new output baud rate into the termios structure.

         tcsendbreak(fd, duration)
              Emit a break condition on a serial line  for  a  time  indicated  by
              duration.  (Always 0.4 seconds under Minix, duration is ignored.)

         tcdrain(fd)
              Wait until  all  output  waiting  in  the  output  queues  has  been
              transmitted.

         tcflush(fd, TCIFLUSH)
              Flush the input queue.  (I.e. discard it.)

         tcflush(fd, TCOFLUSH)
              Flush the output queue.

         tcflush(fd, TCIOFLUSH)
              Flush the input and output queues.

         tcflow(fd, TCOOFF)
              Suspend output.  (Like the effect of STOP.)

         tcflow(fd, TCOON)
              Restart output.  (Like the effect of START.)

         tcflow(fd, TCIOFF)
              Transmit a STOP character intended to make the  remote  device  stop
              transmitting data.

         tcflow(fd, TCION)
              Transmit a START character to restart the remote device.

## SEE ALSO

         stty(1), tty(4).

## DIAGNOSTICS

         All functions return 0 unless otherwise specified, and -1 on  error  with
         errno  set  to  indicate  the type of error.  The most notable errors are
         ENOTTY if fd does not refer to a terminal device, and EINTR if one of the
         functions waiting for output to drain is interrupted.

## NOTES

         It may be interesting to know that the functions operating on the tty are
         directly  translated  into  the  following Minix ioctl requests:  TCGETS,
         TCSETS (now), TCSETSW (drain), TCSETSF, (flush), TCSBRK, TCDRAIN, TCFLSH,
         and TCFLOW.  You should only use this knowledge when trying to understand
         the tty driver code, of course.

## BUGS

## AUTHOR

         Kees J. Bot (kjb@cs.vu.nl)